I actually enjoyed the BF3 campaign (single-player) more than the multiplayer.
The fighter jet mission over the ocean is amazing, as well as the tank mission in the desert, the graphics are so awesome in both levels.
But the AI can get really dumb sometimes and the enemies always seem to know where you are but I still liked it.

The multiplayer just feels clunky and not as "tight" as CoD.
You might see what I mean once you play